This invention relates to pinch roller type automatic drafting machines for applying pressure to paper by drive rollers and pressure rollers to feed the paper in a predetermined direction.
The automatic drafting machines of this kind function in such a way that paper is sandwiched by the pressure of drive rollers and pressure rollers to feed the paper in a Y-coordinate axial direction, and a drawing head is shifted along the paper in an X-coordinate axial direction and a pen of the drawing head is made to contact and to separate from the paper to draw a predetermined pattern on the paper automatically.
The horizontal surfaces of guides for supporting and guiding the paper of the automatic drawing machine are set so that the length is set short in the Y-coordinate axial direction in order to save the entire space of the automatic drafting machine. For this reason, the front and back of the paper are arranged not to be supported by the guides. In this construction, when the paper is fed at a high speed in forward and reverse directions along the X-coordinate axis by a pinch roller mechanism, the free ends of the front and rear of the paper in the feeding direction float in the horizontal direction instead of the free ends hanging down, and thus, the front and rear of the paper collide with objects positioned at the front and rear of the machine or the drawing paper is torn by the wind pressure working on the drawing paper, and the torn portion enters the rollers of the pinch roller mechanism causing trouble in the drawing operation which is a problem. An object of this invention is to eliminate the foregoing problem.